It’s high noon on a balmy summer afternoon in July 2008. You are browsing the shelves of Mesa Public Library in search of a good read.

A search that should be a relaxing and calming experience is instead marked by grave discomfort as a result of the hot and humid conditions in the library.

Many patrons of the Mesa Public Library had experienced these feelings of discomfort during hot days.

To address this problem with our beloved Library, the County Council approved a retro commissioning project to identify and implement improvements that would alleviate the hot and humid conditions. Retro-commissioning is a systematic process that typically focuses on energy-using mechanical equipment and related controls to achieve improved indoor air quality, comfort and energy and resource efficiency.

Anne Laurent, Capital Projects and Facilities Director and Wayne Kohlrust, Internal Services Manager, determined that optimizing the existing evaporative cooling system was the most sustainable and cost- effective option for improving comfort in the library.

“This was the economical option that enabled us to build in more control and comfort while avoiding disposing of a functional system in the landfill,” Laurent said.

Improvements made in the Library include:

1. Increased the number of heating and cooling control points from 35 to 74 to improve temperature balancing throughout the building.

2. Lowered the temperature at which the cooling system turned on to prevent the building from overheating and making it difficult to achieve the desired temperature;

3. Reduced the amount of humidity pumped into the building with outside air by cutting off the inflow when the humidity was higher than 60 percent;

4. Avoided pre-heating the cooling air by rerouting to avoid contact with heating coils;

5. Allowed individual control of relief fans that originally could only be controlled in groups of three;

6. Added tinting to windows to alleviate hot spots.

Since the installation of these improvements in July 2008, the library has been a much more comfortable place to be. According to the Library Manager Charlie Kalogeros-Chattan, “the building is considerably more comfortable and patron complaints have all but disappeared. We will need to double-check the effectiveness of the tinting when the weather gets hot again, since it was completed just as the temperature outside got cooler. One remaining area that needs to be addressed is the solar gain from the skylight. Due to its irregular shape, the solution is still under discussion.”

Along with improving patron comfort the project also served as a valuable learning tool for county employees; “Commissioning and retro-commissioning have become tools in our belt to optimize performance and comfort of county facilities and we are looking forward to measuring the energy savings and comfort performance in the library and taking what we have learned to the next county facility.” Kohlrust said.